Comment 12 for bug 2039251

Broadly speaking they're supposed to be equivalent. The launchpad.net/api one has to continue existing because the Launchpad web UI uses it (to avoid cross-domain issues), and as I mentioned api.launchpad.net is used by the official bindings. I have a very loose feeling that api.launchpad.net is stylistically better for external code as opposed to parts of the Launchpad web UI, but in practice I doubt it makes much of a difference.